1. Field of the Invention
This invention relates generally to a multispectral laser printing system and, more particularly, to a multispectral laser printing system employing efficient optical elements.
2. Background of the Prior Art
Multispectral laser printing systems are well known in the art as evidenced by U.S. Pat. No. 3,975,748, entitled "Multispectral Laser Camera Device", issued Aug. 17, 1976. The aforementioned patent shows a laser printing system embodying a helium neon laser to provide a red wavelength band and an argon laser to provide a multispectral wavelength band having green and blue wavelength components. The multispectral wavelength band is thereafter separated by a beam splitter into its blue and green wavelength components by a plurality of dichroic mirrors which operate to separate the different wavelengths of light in order to enable each wavelength of light to be individually modulated. The modulated red, green and blue wavelength beams are thereafter recombined by another plurality of dichroic mirrors back into a single multispectral wavelength beam which is thereafter directed to line scan photosensitive material in order to record the desired color image. The dichroic mirrors which are utilized both as beam splitters and beam recombiners are generally in the order of 50 percent efficient thus resulting in a 50 percent loss of beam energy each time a multispectral wavelength beam is split or each time two different wavelength beams are recombined into a multispectral wavelength beam. Thus, there is a substantial loss in beam energy as a result of the use of such beam splitters resulting in a substantial reduction in the overall efficiency of the laser printing apparatus.
Therefore, it is a primary object of this invention to provide a multispectral laser printing system in which the high energy losses attributable to beam splitters is eliminated.
It is a further object of this invention to provide a multispectral laser printing system of high efficiency in which beam splitting and beam recombination are accomplished by highly efficient light refracting optical elements.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the mechanism and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.